We plan to continue our study concerned with the structural elucidation of tumor-inhibitory compounds isolated from plant sources in our laboratory. The studies to date have yielded a fascinating array of novel types of tumor inhibitors. Three of these compounds have been deemed sufficiently active to merit large scale procurement by the National Cancer Institute for preclinical toxicological studies, and two are already under clinical investigation. Three additional candidates are now in advanced preclinical testing in slow-growing model tumor systems. We hope that our continuing efforts will yield equally novel results. After structural studies are completed, additional efforts will be directed toward the mechanisms of action of the new compounds, and toward synthesis of new potential therapeutic agents based on the structures of the active natural products.